Publish Next packages

[eric-burel]

Building packages meant specifically for Next is specific. We probably don't need to have a full build process, and we should instead let Next do it's magic as much as possible, directly within the Next user app. Exactly like a Meteor package does not necessarily need a lot of transpiling to be published.

See this discussion for example, regarding process.env in NPM packages: https://github.com/vercel/next.js/discussions/17262

I did a test with next-transpile-modules but did not manage to make it work as expected yet: https://github.com/martpie/next-transpile-modules/issues/120

At the moment, Next packages specific to vulcan are shipped directly with the starter, they are not real NPM packages.